1. Field of the Invention
The present invention relates to a cold air generating device, and more particularly to a cold air generating device of Stirling cycle type in which a brine for transferring cold air and a heat-discharging heat transfer medium are circulated to achieve a heat transfer therebetween.
2. Description of the Prior Art
Referring to FIGS. 1 and 2, there is illustrated a refrigerator equipped with a conventional Stirling cycle type cold air generating device. As shown in FIGS. 1 and 2, the refrigerator comprises a Stirling module (a freezer) 1 for generating a cooling effect according to the Stirling cycle, a heat-absorbing heat exchanger 3 for heat-exchanging cold air generated from a heat absorber (a cold air generating unit) 2 with air in a refrigerator, a brine serving as an operating medium for feeding cold air to the heat-absorbing heat exchanger 3 and having a characteristic of not freezing at a low temperature, and a heat-absorbing-side circulation pump 4 for circulating the brain. The refrigerator also comprises a heat-discharging heat exchanger 6 for discharging heat radiated from a radiator 5 of the Stirling module 1 at air in a room at which the refrigerator is installed, a liquid, for example, water, serving as an operating medium for transferring heat from the radiator 5 to the heat-discharging heat exchanger 6 and having a high specific heat and a high convection heat transfer coefficient, and a heat-discharging-side circulation pump 7 for circulating the liquid. In addition, the refrigerator comprises a cold air circulating unit 8 for feeding air cooled upon passing the heat-absorbing heat exchanger 3 to required parts of the refrigerator, and a temperature sensor 9.
In FIGS. 1 and 2, the reference numeral 13 denotes a linear motor, 14 a piston, 15 a displacer, 16 a regenerator, 17 a compression chamber, 18 a reaction space, 19 a voltage controller, 20 a microcomputer, 21 a voltage controller and 22 a cylinder.
In such a conventional Stirling cycle type refrigerator, a cooling effect is generated at the heat absorber 2 of module 1 and an expansion chamber 10, by the module 1 operating in the Stirling cycle. The generated cooling effect is transferred to the brine filled in a shell 11 of the heat absorber 2. The cooled brine is fed to the heat-absorbing heat exchanger 3 by the heat-absorbing-side circulation pump 4, so that it exchanges heat with air in the refrigerator to generate freezing and refrigerating effects of the refrigerator and circulates continuously. The heat radiated from the radiator 5 of the Stirling module 1 is transferred to the liquid having high specific heat and heat transfer coefficient and filled in a shell 12 of the radiator 5. The heated liquid is then fed to the heat-discharging heat exchanger 6 by the heat-discharging-side circulation pump 7 so that it discharges heat at air in the room at which the refrigerator is installed. By such a heat discharge, the liquid is cooled by itself. The liquid returns to the radiator shell 12 and then circulates continuously.
The above-mentioned conventional cold air generating device includes two pumps one being the heat-absorbing-side circulation pump 4 for circulating the cooling effect generated at the Stirling module 1 to the heat-absorbing heat exchanger 3 by means of the brain and the other being the heat-discharging-side circulation pump 7 for transferring the heat radiated from the radiator 5 of module 1 to the heat-discharging heat exchanger 6. This construction results in a complexity of the overall construction of freezing system and an increase in cost. For obtaining sufficiently an advantageous capacity control being a characteristic of the Stirling freeze, respective capacities of the heat-absorbing-side circulation pump 4 and the heat-discharging-side circulation pump 7 should be varied to correspond to the variation in capacity of the module 1. As a result, a pump with variable capacity is required. There is also required an accessary device for sensing the variation in capacity of the module 1 and controlling the pump according to the sensed variation. These devices make the refrigerator increase in cost.